1. Field of the Invention
The present invention relates to an improvement in a printer having a function for printing dot image data.
2. Description of the Related Art
In a conventional label printer, all contents of print data for one label to be printed are expanded (or drawn) in a memory (image buffer), and the label is then printed to issue. In other words, drawing for one print data and printing for the drawn print data are sequentially performed to issue one label.
According to the above conventional printer, the memory capacity must be as large as to hold the maximum size of all available labels, because all contents of a label to be issued must be expanded in the memory. Thus, the conventional printer requires a large memory capacity, or the maximum length (label size) of printable labels is limited by the active memory capacity.
Further, a conventional printer requires a long print time. That is, according to a conventional printer, printing is inhibited during the drawing operation in a memory and the printing can start only after completion of the drawing of print data for one label.
A prior art printer is shown in U.S. Pat. No. 4,862,194 patented on Aug. 29, 1989 to Uematsu. The printer of Uematsu can handle a large label whose one image size may overflow the limited capacity of an image buffer.
More specifically, according to Uematsu, a large label image is divided into several pieces, and each of the divided images are expanded or drawn into the image buffer for many times, thereby alternatively repeating the drawing and printing operations. Thus, the printer of Uematsu can print a big label having an image size larger than the actual memory size of the printer.
According to the printer of Uematsu, however, the speed of print processing decreases with increase in the number of division of the label image.